Multichannel start-stop telegraph system



July 21, 1942. P. L. MYER ETAL 2,290,201

MULTICHANNEL START-STOP TELEGRAPH SYSTEM Filed Jan. 10, 1940 3 Sheets-Sheet l l FIG. I 68 U 3O INVENTORS P. L. M Y E R ER WHEELER TO-FY25.

RECEIVER 5 Sheets-Sheet 2 P. L. MYER ETAL MULTICHANNEL START-STOP TELEGRAPH SYSTEM Filed Jan. 10, 1940 July 21, 1942.

INVENTORS P.L.MYEIR I E.R.WHEELER July 21, 1942.

L. MYER ETAL MULTICHANNEL START-STOP TELEGRAPH SYSTEM- Filed Jan. 10, 1940 TRANSMITTER 3 Sheefcs-Sheet '5 FIG. 3

INVENTORS P. L.MYER

BY E.R.WHEELER' TORN;

Patented July 21,1942

wUNI D* ST T Percy L Myer, Ozone Park,

Wheeler Plaizn'field, N. 1.,-

I -'Western Union Telegraph Company, New York, N.'Y.-, a corporation of NewYork I Applicati n January i0, 19ip;"s na1 n s sg ws I r I llClaims'. (o1. 1731-52) This inyention relates to signaling systems,

and more particularly to expanding channel systems whereina communication channel is:

shared by a variable number-of subcharmels or sources. of telegraph signals,

.The term expanding channel as used here-tin refers to a system in which ayariablenum:

ber of telegraph transmitters or othersending,- devices are arranged to control, receiving devices corresponding, to each sending deviceover a communication channel, substantially the entiresignaling time of the communication channel N.'Y., na'cvann.

assignors to The anthemidentifying signals.

' Another object of the invention is td'pr'ovide an expanding channel system in which the entry" and exit of subchannels is efiected 'withoutthe loss of normal intelligence signaling time over i the communication, channel.

I Another an expanding channel system employing a single transmitting distributor. which may be controlledwhenone' or-more subchannels is'operative and being divided among the operating transmitters 1 and,v receivers. The expanding channel. system thus comprises acommunication systemin which the number of subchannels. operatingover, the; circuit connectingthev transmittingand receiv-g ing stations 'may be expanded or contracted by cutting in or out corresponding transmitting and receiving devices, .the operative .subchannels;

sharing the communication channel. The pres-,-

ent invention'relates particularly to aprinting' telegraphsystem of this character in which mes.-

sage characters are" sent in 1 sequence ;from one busy subchannel transmitter after another omit.-,

ting the'idle or inoperative subchannels.

'Oneobject of the present invention is to provide an expanding channel system operating over a communication channel on a start-stop= basis.

Another object of the invention is to provide:

a'n expanding channel system having, a relay for;

object of the invention "is to provide from anysubchannel to rotate "continuously 'w'hi'ch'is stopped when no subchannels are opera ative.

iothcrflmore specific ob ects will become ap parent from the following description which is taken in conjunction; with the accompanylng" drawings, of which:

Figs. land 2 represent diagrammatically the transmitting apparatus employed to operate an] expanding channel system of the character described having four subchannels;

4 V Fig. 3 is a diagrammatic representation of the channel disclosed herein.

detailed circuits, is as follows:

Thetransmitting station equipment shown in Figs. 1' and2 includes a transmitting distributor TD bywhichj a transmitting relay'5 l is operated to send signals over line L., Each subchannel,

each "subchan'nel to connect the. subchannel ap-i paratus to the communication channel 'an'din which novel means are employed. vfor successively actuating-the relays associated with oper-j ative subchannels. "Another object of the invention is to providean improved relay chain for controlling a. multiplicity ofcircuits, more particularly to successively select operative subchannels for operation, were communication channel; AIlOlShEILObjCfi of the invention is to :provide an expanding channel system *in which; each character which is transmitted over the com.- munication channelcontains signals by which the transmitter from which may be'identified. Another object of the invention is toprovide an" expanding channel system in whichmeach I I ,character includes'a subchannel identification signal and inwhich the receiving, apparatus is arranged to utilize the identifying signals to associate the proper receiving instrument with the communication channel,the receivirigyequip such a's'subchannel A, is provided with a tape transmitter EZ and a connector relay 53'having a plurality or armatures including armatures 54 by which the transmitter}! are transferred to aisegmented the character is sent ring 56 of the transmitting distributor 'I'D when the connector relay is operated. When thecrelay 53 ,is in its unoperated position, the tongues 54 in cooperation with theirrespective back contactsare arranged to detect the presence of an intelligence character perforated in a tape'Bl when the character is advanced to a position to be engaged by the pins of the transmitter. The detection of. an intelligence character in' the transmitter results in the operation ofarelay 58 which, at a prearranged time, operates a cut in relayja, As long as the transmitterizf is i being supplied with} tape in which intelligence charactersiare perforated, the cut-in may-59 remains operated thereby maintaining the sub-j channel in operative association with the line -:1-

,. Each ofv theother 'subchannels 3,0 and!) is provided with transmitting apparatusfljsimilar designed to subsequently delete the 5' receiving apparatus employed in the expanding "signal. combinations set up in the to that shown in detail for subchannel A. When all of the subchannels are in an operative condition, the connector relays such as 53 of "subchannel A, are operated successively to connect their respective transmitters one at a time to the transmitting distributor TD. The operation of these connector relays is controlled from a pair of local rings 6I and 62, on the transmitting H distributor ID. The passage of brush 63oversegment 64 of ring 62 applies a potential to conductor 8 of cable 66. This'conductor is connected in multiple to one winding ofeach of the connector relays such as 53 of subchannel A. However, the circuit through only one 'of these relays is completed at any one time. Each ofthe circuits extend through a front contact suiiicient length is formed in the tape 51 to per- 'mit the engagement of the tape lever I04 with its contact I06 whereby a potential is applied to conductor of cable I0'I. At this time a relay I08 .-is unoperated-since none of the subchannels are of its associated cut-in relay 59, 61, 68 and 69. The circuits interconnecting these latter relays" are carried through contacts of the relaysand also through the contacts of a set of switching relays II, I2 and I3 in such a manner that the operating circuit for only one of the connector relays such as- 53.of subchannel A is complete at any one time. The switching relays II, I2 and 13 comprise arelay chain by which the operating circuits for the connector relays are selectively completed in succession.

The connector relay 53 of subchannel A is also provided, with armatures I4 and I6 which are adapted to connect a combination of signals individual to this subchannel to segments 11 and I8 respectively of transmitting distributor ring 56 whensubchannelA is connected to the communication channel. It will'be noted that these.

signals are transmitted before the character signals and are used as subchannel identifying signals. Each of the other subchannels B. C and D is provided with similar signaling facilities for the purpose of identifying the character signals with the proper subchannels. I V

The signals transmitted over the li ne L are received by a line relay I9 of Fig. 3 and transferred by means of a receiving distributor RD to a plurality of relays. The subchannel identifying signals are transferred by means of segments 8 I-and.82 of the receiving distributor ring 83 to subchannel selectin'g'relays 84 and 86. These relays prepare a-circuitto one of the receiving con nector relays 81,86, 89 or 9|. The receiving connector-relay selected is operated by means of a local impulse generated ,by a segment of ring 92 to connect one of the receiving devices 93, 94, 96, or 91 toan auxiliary distributor RAD.

- The, signals representing the intelligence characters are transferred from ring 83 of the receivingdistributor- RD to a bank of storage relays 98. The signals stored in this bank are transferred to the segmentsof. ring 99 of the receiving auxiliary distributor RAD, and the brush I0l of this distributor is. periodically released for rotation over the segments of ring whereby the signals are transferred to one of the receiving devices 93, 94; 96 or 91. v A better'understanding' of the invention may be obtained from the following detailed description of typical circuits in'the system. When all of the subchannels are idle the transmitting, receiving and receiving auxiliary distributors TD, RD, and RAD'respectively are held in their idle or,rest positions as shown in the drawings. When a'character signal which is perforated in the tap 51 of subchannel A is stepped into the transmitter 52 by means which will be described subsequently, one of the tongues of the transmitter in operation. Consequently the engagement of armature I09 of this relay with its back contact energiaes winding III of an entry relay H2. Thus, the potential which is applied to conductor 20 of cable I'0'I is transferred by means of one of the armatures H3 and its associated front contact of the entry relay II 2 to energize winding H4 of the cut-in relay 59 of subchannel A. The

operation of the armatures of this relay 59 to their respective front contacts eflects, among other things, the locking of the relay through its armature H6 and winding III to the battery' which is applied to conductor 20 of cable I01 from 2 the tape controlled contact I06. I

The engagement of armature III of cut-in relay 59 withits front contact energizes the winding of relay I08 which has a slow-to-operate characteristic so that'relay 59 may be securely 5 locked before the armature I09 of relay I08 is disengaged from its back contact. When this disengagement does occur, relay I12 is released thereby opening the operating circuitof relay 59., The engagement of armature I09 of relay I08 with-its'front contact closes a circuit which may be traced from the battery connected tear-.-

mature I09 through its front contact,. conduc--v tor I9 of cable I01 to the winding of release magnet II8 by which the operation of the transmitting distributonTD is controlled. Upon the energization of th winding of release magnet H8,

a latch H9 is removed from the path. of the brushes 63 and I2I of the transmitting distributor, thereby permitting these brushes to traverse the distributor rings associated therewith.

The engagement of brush 63 with segment 64 of ring 62 closes'a circuit which may be traced from the battery of ring 6| through the brush 63,. segment 64 of ring 62, conductor 8 of cable 66, winding I22 of connector relay 53, the winding of relay I23; conductor 22 of cable I01, armature will be moved into engagement with the marking I24 of cut-in relay 59 and its associated front contact, back contact and armature I26 of switching relay II, back contact and armature I21 of switching relay I2, back contact and armature l28 of switching relay "and through the winding of a locking relay I29 to ground. The completion of this circuit causes the operation of relays 53, I23, and I29; The operation of locking relay I29 energizes an auxiliary. locking winding I3| of cut-in relay 59 through armature I32 and front contact-of this relay. It may be seen that similar arrangements are made for any of the cut-in relays 59, 61, 68 or 69 which may be operated at the time that a selecting impulse I I4 andIIi by meansof conductors I and'2 of cable 66 to segments I1 and I8, respectively, of

ring 56 of the transmitting distributor TD. Also the engagement of the"armature s 54 with their.

respectivefr'ont contacts transfers. the signal means of conductors 3 to 1, inclusive, of cable 63 to the other segments of ring 56.' The engagew ment of tongue I33 of relay 53 with its front contact supplies battery to maintain the operation of relay- 58. This relay has a slow-to-release characteristic to prevent the release of its armature during the transfer of its operating circuit, from the transmitter 52 to the armature I33 of relay 53. The operation of relay I23 disengages its armature I34 from its back contact, thereby opening a circuit'which is otherwise prepared by the engagement of armature I36o f connector relay 53 with its 'front contact.

nal by which: subchannel A identified comcombinationset up in the transmitter-P52 by 1 prises two--'markingimpulses and these signals aredistributed to segmentsIII and 82 of ring 83 from; which-they are transferred by conductors 33 and 34,"res'pectively, of cable I48 to the-chanhel selecting relays-84 nd-as; both or these relays are operated. These relays/are {locked through their respective armaturesjl49fa'nd" I5I and their associatedfront contacts and through The movement of brush 63 of the transmitting distributorTD from segment 64 to segm'ent I31] of ring 62 opens the circuit through winding I22 of relay 53, the winding of relay I23 and the winding. of relay I29. Relays I23 and I29 are released but the brush 63 with segment I31 of ring 62 completes immediate engagement of 1 back contact and armature I52 of lockingrelay As the brush m of the receiving distributor RD travels over.v the other segments of ring 83, --the co'ded character sig'nals are transferred by Y 115 v "storage relays I68 and I59 are looked through a circuit from the battery connected to ring 6| through conductor 9, of cable 66 through wind ing I38 of relay 53 armature I39 and front'contact of this relay and winding I H of the entry relay 2 to'ground. Thus the connector relay 53 maintains its armatures in their operated positions andthe armatures of the entry relay II2 are moved into engagement with their respective front contacts so that any of the cutin relays 61, 68 or 69 may be operated in a manner similar to that described in connection with relay 59. Also the release of relay I23 closes a circuit from battery through afront contactjand the back contact and armature I63 of locking relay I64. A typical locking circuit extends V from'the battery connectedto armature I6I of relay I62 through the back contact associated therewith, the armature I66 and front contact of storage relay I54 and the winding of this relay to ground. Just prior to the transfer of the Y character signals to the bank of storage relays 98, the brush I61 of the receiving distributor RD is engaged with segment I68 of ring 92. A-circuit is vthus completed from. the battery conarmature I36 of relay 53, back contact andlarmature I 34of relay I23, conductor -2I of cable I01 and the winding of switching relay'1l to ground, thereby operating the armatures of the latter relay to their respective front contacts.

The signals which are set up at the transmitting position of sfubchannel'A' are also set upon thesegments of'ring56 ofthe transmitting distribtor TD. As. the brush 63 is traversing the locking segment I31 of ring 62, the brush I2I is traversing successivelythe segments of ring 56, thereby transferring the signal com bination set up thereon to operate the transmittingrelay 5I. In this manner the signals representing the identificationof-subchannel A nected .to ring I69 through the brush I61 and segment vI63,.conductor 45 of cable I1I,through the windingmof'relay I62 to ground. This relay becomesfenergized to open the locking circuit for storage relays I54, I56 and I51, theserelays'being restored to their vnon-selected positions. They are now in condition to receive the first three impulses .of the first character sent over th'e'line from the transmitter of subchannel A.

-While these signals are being stored, the receivingdistributor brush I61 engages segment I12 01 ring 92' to momentarily energize locking relay I13, over conductor 46 of cable "I.

The disen- "f'gagement of armature I14 of relay I13 from its together with a character -codecombinationnare transmitted over the line L. 'It will be noted that as soon as the brushes 63 and I2l are released for rotation the brush I21, becomes enback contact opens a locking circuit through an "operated one of the receiving connector relays B1 to 9|, inclusive. stored to their unoperated positions in readiness These relays are thus all reto receive a new channel selection. A typical locking circuit for one of these relays extends gaged with segment I42 of ring 56.v The transmitting relay 5I which, during the idle condition of the transmitting distributor TD maintains send aspacing signal over 'tlieline.

The spacing 'or start signal which is thus transmitted is receivedfiby-the line relay 19 of Fig. 3, the armature I43 of "which is disengaged from its" marking contact to which battery is connected. The circuit through the brush I44 of the receiving distributor RD and the winding I46 of the release magnet is'thus opened causing" the release of the magnet 'arma tureto with draw the latch I41 from the" from the battery connected to tongue I14 of reflay I13 through the back contact associated therewith, the front contact and armature I16 of relay 81 and the winding oi this relay'to marking potential on the line, is operated ,to v

ground. Immediately after the described restoration of the receiving connector relay, the receiving distributor brush I61 engages segment I11 of ring 92 to'close a circuit extending from "the battery connected to ring I69 through con- 1ductor41 of cableI1I, armature I18 and front contact of channeLselecting relay 86, armature I19 and front contact of channel selecting'relay are du'ctor 48 of cable I1 I}? The" disengagement of armature" I 63 of this relay from'lts back contact opens the locking circuit through the storage relays I58 and I59, thereby rendering these re received thereby will have been stored by relays I54, I56 and I51. The ones of these storage relays which have received marking or selecting impulses will be operated and looked as described. Each of the storage relays is provided with a second group of contacts by which the signals stored thereby are transferred to the segments of ring 99 of the receiving auxiliary distributor RAD. One such group of contacts includes the armature I82 and its front contact of storage relay I54 which, if operated, connects battery through conductor 48 of cable I83 to the first segment of ring 99. Thus, by the time that the brushes I44 and I61 have traversed their respective rings sufficiently to effect the engagement of brush I61 with segment I84 of .ring 92, there is set up on the first three segments of ring 99 of the auxiliary distributor RAD a combination of selecting and non-selecting signals. The engagement of brush I61 with segment I84 closes a circuit through conductor 49 of cable I1I to energize the Winding of the release magnet I86 of the receiving auxiliary distributor RAD. Thus, latch I 81 of this distributor is withdrawn to permit the rotation of brush IIlI over the segments of the auxiliary distributor.

The continued rotation of brush I44 of the receiving distributor RD over the remaining two segments of ring 83 results in the storage of the fourth and fifth character signals in the storage relays I58 and I59 respectively. During this time the brush I61 engages segment I88 of ring 92 to energize the locking relay I53 over conductor 50 of cable IN. The operation of this relay momentarily opens the locking circuits through the channel selecting relays84 and 86,.permitting these relays to be restored, preparatory to effecting a new channel selection.

By the time that the brushes I44 and I61 of the receiving distributor RD have completed their traversal of their respective rings, the brush "ll of the receiving auxiliary distributor RAD 'will have started its traversal of the segments of ring 99. The successive engagement of these segments by the brush IUI causes the signals stored in the receiving bank of relays 98 to be transferred through the front contact and armature I89 of the receiving connector relay 81 to the winding of the selecting magnet 93 of the receiving device of subchannel A. Thus, the signals repre senting the first character sent over subchan nel A are received by the printer or other translating device associated with this channel.v

Referring again to Figs. 1 and 2, let it be assumed that all of the subchannels A, B, C and D have been connected to the communication channel as described in detail for subchannel A. Also assume that the first character has just been transmitted from subchannel A, as described. It will be noted that as long as any of these subchannels are operatively associated with the communication channel, relay I08 remains operated under the control of one or more of the relays 59, 61, 68 and 69. Thus, the circuit through the winding of the release magnet II8 of the transmitting distributor TB is maintained in a closed condition, resulting in the sustained retraction of 'he latch H9. The brushes 63 and I2I are therefore permitted to revolve continuously over their respective rings. Following the-transmission of the first intelligence character from subchannel A, when brush 63 of the transmittin distributor TD becomes disengaged from segment I31 of ring 62, the locking circuit through winding I38 of connector relay 53 and winding I of the entry relay I I2 is opened thereby permitting the'release of the armature of these relays. The opening of the contacts of the entry relay II2 prevents the operation of any of the cut-in relays 61, 68 or 69 in the manner previously described in connection with the operation of cutin relay, 59. Hence, it is impossible to enter any subchannel into operative association with the communication channel during the disengagement of brush 63 from segment I31 as long as there is one or more of the subchannels already operatively associated with the communication channel. The only case in which asubchannel may be prepared for connection to the communication channel when the brush 63 is not engaged with segment I31 of ring. 62 is the one previously described when all subchannels are idle. The disengagement of armature I36 of connector relay 53 from its associated front contact deenergizes the winding of switching relay H, but this relay has a slow-to-release characteristic so that its armatures I26 and I92 are not immediately disengaged from their respective front contacts, but are maintained, in their operated positions while the transmitting distributor brush 63 is traversing segments I9I and 64 of ring 62 in the succeeding revolution.

.The engagement of brush 63 with segment I! of ri'ng'j62 closes a circuit through conductor I8 of cable I01, through the front contact and armature I92 of switching relay 1|, conductor ll of cable, I01 and through the winding of the stepping magnet I93 of the transmitter 52 to ground. The energization of this magnet performs the functions of withdrawing the pins from the tape 51 and stepping the tape through the transmitter to bring a new character code combination 'into association with the transmitter pins. The disengagement of brush 63 of the transmitting distributor TD from segment I9I opens the described circuit through the stepping magnet I93 of transmitter 52, thereby permitting the pins of the transmitter to move into engagement withthenew'character perforated in the tape 51. The slow-to-release characteristic of relay 58 prevents the release of the cut-in relay 59 duringthe short time that the transmitter tongues are disengaged from the marking bus bar because of the withdrawal of the transmitter pins from the tape. 1

The engagement of brush 63 of transmitting distributor TD with segment 64 again applies battery to conductor 8 of cable 66 by which the potential is applied to the windings of all of the connector relays such as winding I22 of relay 53 of subchannel A. This time, however, the cir-' cuit through winding I22 of relay 53 is open at the back contact associated with the armature I26 of switching relay 1|, thereby preventing the operation of the connector relay for subchannel A. However, there is established a circuit similar to the one described in connection with the apparatus of subchannel A through conductor 8 of cable 66, a winding of the connector relay for subchannel B, conductor 26 of cable I01, front contact and armature I94 of cut-in relay 61, front contactand armature I26 of switching relay 1|, back contact and tongue I21 of switching relay 12,' back contactfand armature I 28 of switching relay Bend the winding of;v lockingrelay I29 to ground. Inthismanner thezconnector relay-as-z sociated with subchannel B- is operated to con'-' meet the tongues of the transmitter associated with this subchannel to the segments of ring 56 of.

the transmitting distributor TD. Also, theoperation of the connector relay of subchannel B transfersthe channel identifying signal to seg-' ments 11 and 18 of ring 56. In this case armature I96 of the connector relay applies a spacing or non-selecting signal to segment ..11 of ring 56 and armature I91 applies a marking or selecting signal to segment 'IB-of ring 56. a The transmission of the channel selecting and character signals over the line L is effected in a manner similar to that described-for subchannel A. At the receiving station of Fig. 3 theoperation of the apparatus is substantially the same as that previously described. .-In this case,1however,'

the subchannel selecting signals. result only in the operation of-subchannel selecting relay 86 so that when the locally generated impulse is applied to conductor 41 of cable. I1l it is conducted through armature I18 and front contact of relay BG'andarmature :I19 and back contact of relay 84 to operate the receiving connector relay 88.

by means'of which the receiving device 94, associated with subchannel B, is conditioned to receive the signals sent from the transmitting equipment for this subchannel.

Upon the third traversal of the ring 62 of the transmitting distributor TD by the brush 63, the tape, stepping, function of the transmitter associated with subchannel B is performed in a manner similar to that described in connection with subchannel A. It will be noted that, by this time, the armatures of the switching relay H are restored to their respective back contacts, thereby extending the operating circuit of the armature 202 and its associated front contact of relay 84 to-operate the receiving connector relay 89.- Thus, the coded charactersignals which are subsequently received are connected to the selecting magnet 96, of the receiving device associated with subchannel C. r e

The fourth selecting impulse generated by the transmitting distributor. TD is conducted through a circuit including the operating winding of the connectorre lay for subchannel D through conductor 32 of cable I01, the front contact and armature 203 of cut-in relay 69, the front contact and armature I28 of switching relay 13 to the winding of thelocking relay. I29. The connector relayfor subchannelD is thus operated to connect the-tape transmitter. associated with this subchannel to thetransmitting distributor TD. Since the circuit for operating the connector. re-

7 layof subchannel A is open at the back contact associated with armature I 2B of the switching relay 13 and the corresponding circuitsof subchannels B and C are open respectively at the front contact associated with armature I26 of switching relay; H and, the front contact associated with armature I21 of switching; relay 12, the respective connector relays are-not operated. In this case the subchannel identifying signal comprises-two spacing or non-selecting impulses set up on the armatures 204 and 205 ofthe con-.

nector relay.

At the receiving station the subchannel select- 5 ing signals do not operate either. of the subchannel selecting relays ;84 or 86. Hence, the

- locallygenerated impulse which is applied to connector relay .53 of subchannel'A tothe back contact associated with armature I21 of the switching relay 12 at which point it is open since the armatures of relay 12 have not been released. Also, the operating circuit of the connector relay of subc'hannelB is open at the front contact as-' sociated with armature I26 of the switching relay 1I Therefore, the connector relays of subchannels A and B are not operated during the third selecting period. The third selection impulse generated by the transmitting distributor is conducted through the operating winding of.

the connector relay of subchannel C, through conductor 29 of cable I01, the front contact and armature I98 of cut-in relay 68, the front contact and armature I21 of switching relay 12, the back contact and armature I28 ofswitching relay conductor 41 of cable I1I is-transferred by armature I18 and back contact of relay 86 and arma-.-

ture 202 and back contact of relay 84 to the winding of-the receiving connector relay 9|. Thus, the coded character signals which are subsequently received are switched to the selecting. magnet 91 of the receiving device associated with subchannel D.

During the operative connectionof subchan nel D'with the line L, the armature I28 of switching relay .13 is restored to its back contact. Hence-when the fifth subchannel selection is made, following the transmission of an intelli gence character from subchannel D, th operating circuit through the winding I22 of connector 13 and winding of the locking relay I29 to ground.

In this manner, the transmitter for subchannel C .is connected to --the line transmitting equipment'to send a character from this subchannel. In this'case the subchannel identifying signal connected to ring 56 of the transmitting distributor TD comprises a marking or selecting impulse set up onarmature I99 of the connector relay for this subchannel and a spacing or nonselecting impulse set up on armature 20I of the connector relay. 5 g V The receipt of this subchannel identifying or selecting signal at the receiving station of Fig. 3'

causes the operation of the subchannel selectin relay 84. Hence, at the proper time the locally generated impulse is .connectedby means of conductor 41 ofcable "I through the armature I18 and its associated back contact of relay 86 and relay 53 is completed as previously described. It will be noted that the slow-to-release relay 206 of subchannel D. has no control over the selection circuits, its sole function being to assist in stepping the tape through the transmitter.

The operation of the system when all four subchannels are busy-continues in the manner described until one ormore of the subchannels becomes idle. An idle condition of one of these subchannels is'manifested by the perforation in the tape such as 51 of subchannel A of a blank character, thatis, one having no marking impulses. Such a-character is detected by the armatures 54 and their associated back contacts of connector relay 53. Since none of the tongues of the transmitter 52 are engaged with the marking bus bar I02 because of the all-spacing character perforated in the tape, the operating circuit through the winding of relay 5B is opened,'

thereby permitting the armature I03 of this relay to become disengaged from its front contact and engaged with its back contact. The disengagement of this armature from its front contact opens thelocking circuit, including conductor 20 of cable I01 and armature H6 and its associated front contact of cut-in relay 59, through the winding H4 of this relay. If the described locking circuit is opened at any time otherthan' that when the brush E3 of the'transmittin'g .di tributor TD is engaged with"segm"ent; 64', thearmatures of cut-in relay '59 are restored to their back contacts. It will be noted that-as previously described, the resto'ration" of' tlresearmatures cannot be effected during'theselecting period by reason of the fact thatlocking relay I29 is operated, thereby'holding the 'cut-in relay 59 operated through the energization of winding I3I thereof. HoWeven'itjwi-ll be'obvlous that after the release of relay 58and after-the termination of the selecting period;, 'the 'c'ut-in relay 59 may be released as described. J

It is a common-operatingpractice in-systems of this nature to feed 'out' f'rom the tamper: forating device a suitable length of tape in which blank characters are perforated: Theseblank characters are of an all-spacing nature. The

purpose ofpreparing this=blanktape is-to'insurc that all of the'tap'e in which character-signals are perforated is stepped through the transmitting device; However, it has been seen that as soon 'as' the first blank character has-been stepped into the transmitter 52, subchannel A becomes-disa'ssoeiated= from the-communication channel; but-it will'be app'ar'ent'that; between successive groups-of character signals, a series of blank perforations willbe made in the tape; and

that allot this blank tape must be fed'throug'hthe transmitter before the second group ofchar: acter signals canlbe transmitted. 'Also','it-is' obviously undesirable to" transmit thes'e blank chartransmitting station an auxiliary distributor TAD. This distributor comprises "a, pair of seemented rings201 and 208 which are traversed by a continuously rotating brush 209: The op-- eration of this distributor is entirely independent of the transmitting distributorTDand'in order to expedite the stepping of-blank tapethrough the transmitters, it is desirable-that the brush 209 be arranged to traverse the rings 201 and 208 substantially as fast as th tape stepping mech anism of the transmitter will operate;

With a loop of blank tape 51 formed between the transmitter and the perforating devicelthe' release of armature I03 of relay'58 to'jits back contact connects the battery associated with con tact I06 through the tape lever I04 and conductor I0 of cable 66 to segment 2 of ring 208-"o f the transmitting auxiliary distributor TAD. "The engagement of brush 209 of this distributor with segments 2H and 2I2 of the rings 208 and- 201 respectively further extends this circuit through conductor I4 of cable I01 to the-winding I93 of the stepping magnet of the transmitter 52. "Thusit is seen that successive revolution of the brush 209 of the transmitting auxiliary distributor TAD revolutions of the brush 209 of the auxiliary distributoi TAD; are 'inefiectivet to cause further stepping oi -.the-.tape' sinceithe: source .of potential is disconnected-from the stepping magnet circuit; This condition"prevails :untillat a *l'atertime a second group of :character signals is perforated in thezta'petlxsnlengtheningof the. tape loop thensf'o-llowsgz causing theyreehgagement of the tape 'lever, 1.0.4 with contact I06; and thestep- Y ping of'the" remainder-of the blank tape through 3 the -transmitter-:52= continues as described. When the first1intelligence= chairacter'perforate'd in the tape is advanced.-.intoroperative association with the pins of ;,the transmitter, this-: condition" isdetected in a mannerapreviously described and subchannel'A prepared :forentryzinto theiexpanding channel 'system.-

,:From the foregoing description it is seen that withall'subhannels busy, the operating circuits fort-he connector relays of the various subchannels,"except subchannel A, are completed through a contact of one ofthe cut-inrelays 61, B8 or 69 corresponding' to the subchannel" to be operated andthrough thesfront contact of the switching relayII; 12 or 13 corresponding to the subchannel operatedlimmedia'telypreceding the selected subchannel.. In the caseof 'subchannel A which is. operated after subchannel D the circuit for the operation of connector relay 53 includes contacts 'of 'cut-inrelay 59 and the back contact of the switching relay- I'I .associat'edwith subchannel A. Thus it is seenthat there is provided a chain of:contacts including' armatures I2B,eI2'I and I28 respectively of the switching'relays "II,

. I2.and 13' in cooperation with their respective back contacts-leadingto ground through the winding. of locking relay I29, Withall four of the ,subchannels operating ithasbe'en' shown how eachof the circuits for the operation of thechain-of contacts; v

'1 However, when a subchannelis .idle the operatingicircuit for the connector relay of the subchannel'succeeding the-idle subchannel in the prearranged operating sequence of the'subchannels is open at the front contact of the switching relay associated with the idle subchannel. Provisions are 'made to exten'd the circuit from the front contact of the idle switching relay to the corresponding-front contact of the switching relay associatedwith the subchannel preceding the idle subchannel in the sequence. For example, if subchannel C 'is-idle, its cut-in relay 68 is de-energizedthereby connecting the front contact associated with the tongue I28 'of the switching relay 13throughthe back'contact and armature effects successive tape stepping operations intransmitter 52. The stepping of the blank tape continues until th loop of tape becomessufiiciently short to pivot the tape lever I04 out of engagement with contact I06. Thus, succeeding I98 of relay 68 to the front contact'associated with armature 121 of the 'switching relay I2 of sub'channel' B. Hence, following the operation of subchann'el'B', the selecting impulse can not cause the operation of the connectorrelay of subchannel C' since the-circuit therefor is open at the front -conta'ct associated witharmature I98 of the 'cut-in'relay 69 of this subchannel. However, the' circuit-for operating the connector relay for'sub'channel' D is c'orn'pletedthrough the back: contact and armature I98 o'f cut-in relay 68' and through the front contact and armature I2! of switching relay 12 through the remainder of the'contact chainto the'g'round connected to locking relay I29 Thusfsubchannel C is omitted from the sequence and subchannel D is opeiated iminediate'l'yfollowing the operation of subchannel=B.' Inthe eventthat subchannel B is also'idle; the front contact associated with with the -communication channel;

armature l2! of switching relay 112 is connected by means of the back contact andarmatur'e' N4 of-the cut-in relay B'I of subchannel B to the frontcontact -'associated with armature I 26 of switching 'r'ela'y'Tl of subchannelA; Similarly, if subchannel A is also inoperative the front contact associated with armature-I26 of itsswitchmg relay ll" isjco'nnected by means of the back contact and armature'2l3 of-the cut-inrelay 59 of subchannel A to the back contact associated with a'rm'ature 121 of switching relay "of subchannel-B. Thus, it is obvious that whenasub-j channel is idle another subchannelhavinga position' following the idle subchannel in the pre: arranged sequence may be 'operated by providing access to the contact chain at a point-associated with a subchannel having a position preceding that of the idle subchannel in the Se quence. V e c 7 Since the described chain of cont'actsdoes not include any of the apparatus of "subchannel D,

operation of this subchannel has no controlover of the contact chain to its normal or idle condi-,

tion. It should, therefore, be'fobvious' that with any arrangement of operative-subchannels, "in-1 cludingsubchannel D, and of inoperative subchannels, the contact chain can not be open'at a point asso'ciated'with a subchannel following in the sequence of a subchannel to be connected Therefore, the operation of the system under these conditions employs only the circuits described up to this point. However,- there'are' conditions occurring when subchannel D 'is idlewhen the contact chain willat some time'or-another be open, either completed in the normal mannerby entering the ing alone); or at the switching relay of a subchannel'ha'ving a position in the sequence following-that of the subchannel to be selected. In 1 any of these cases the previously described circuits which aiford access to the contact chain from a point above that of the normal entry into nont contact andiar niaturefz l v main contact chain by way of the jswit-chin'g apparatusla'ssociated with .subchannel A since this contact chain stands open, at the back contact associated with armature I28 of switching relay 13; Under these conditioris the operating circuitjior the connector relayo'fgsubchannel B includes,.conducto r 26' of cable 191- the front contactand armature l'9' l of cu;- 'relay 6], the of his relay, the back contact; and armature 2 relay"59 of subchannel .Aftheback contact and armature 20 3 of the cut -in .frelay 6 9 ofrsubchannel D, the, front" contact and armature 128 of switching relay 13and'thewndingmof locking relay 129; It is believed th edetailed description of these typical circuits' wilibe sufficient to enable one skilled in theart to trace any of the'oth'er possible operating circuits. for the respective subchannel connector relays when the subchannels are grouped in. any of the possible arrangements of operative-and inoperative sub channels.

The successful. operation of printing telegraph system depends upon the maintenance of synchronism between the transmitting and r'e-.

ceiving. apparatus. In the expanding "channel system disclosed herein three distributing elemerits are employed, one at the transmitting station and two at the receiving station. As described in an earlier portiongof the specification when one or more of the subchannels is associated with the v cor'nrnu'nicationv channel .the latch I IS of Fig.2 is held Withdrawn from the path of the brushes 63 and lfl of the transmitting distributor TD thereby permitting these brushes to rotate continuously over their respective rings. Consequently it is necessary to m0- men'tarily arrest the rotation of the receiving.

distributor brushes Hfia nd |'6'| of Fig. 3 after each traversal of their associated rings. By doin this, it is possible to start thereceiving brushes cess-to the contact chain froma point below'that of its'norm'alentry into the chain. For this pur pose an auxiliary chain of contacts is providedand extendsfrom the armature 2H ofthe cut-in relay68 of subchannel C through the back contact. and armature MB of the'cut-in relay 6! of subchannel B, the back contact and armature! of the cut-in relay 59 of subchannel A, the back contact and armature 203 of the-cut-in relay 69 of'subcha'nnel D, to a point 218 from which access to'the contact chain is afforded in the man- H ner previously described.- The front contacts associated with arm'atures 2 i1, H6, 2 l4, and 203 are to the described-auxiliary chain of contacts; By

wayof illustration,-assurne that subchannels B and Care operating over the communication channeland that a character has just been simultaneously with the b'eginning ofa cycle of rotation of the transmittingdistributor brushes 63 and IZI as described. In order to effect the ,proper operation of the receiving distributor ranged totraverse itsrespective rings at a slight- ,ly hi'gher rateof speed than the receiving distrib'utor RD. The relative speeds of the various distributors, employed herein are susceptible of an appreciable variation to suit each particular use of the'systern. It has" been found that satisfactory results may be obtained by operating the transmitting distributor TD at a speed "of 390. 12.1; M., the receiving distributor RD at a speed of 405 R. P. M. and the receiving auxiliary distributor RAD at a speed of 420R. P, M. It will be understood that these speeds are merely by way of illustration and are not to be construed as a limitationof thei'nve'ntion disclosedherein. From the-foregoing description it is apparent that each of the subchannels forming a part of the expandingchannel system is provided with a transmitter and a receiver. Each subchannel is also provided with suitable connecton relays for associating a subchannel transmitter and its cor responding receiver with'a communication channel. These connector relays areoperated in pairs, one at thetransmittin'gstation and meat the receiving station in succession so that all of the busy subchannels are given an opportunity ,to operate and each operating subchannel shares the signaling time of the communication channel with the other busy subchannels. The transmitting connector relays are operated successively in a prearranged sequence and provisions are made for omitting the idlechannels from the sequence. The'busy condition of'a subchannel causes the operationof a cut-in' relay associated with this channelso that'itmay be included in the operating sequence' of thebusy subchannels. The sequential operationof the connector relays associa'ted withbu'sysubch'annels is'eifected by means of-a group of '-ir'iterc'onnectt-zd switching relays, onebeing associated with each subchannel.

Each character signal which is transmitted over the-communication channel contains additional signals by which the subchannel over which thewchai'a'cter is being sentis identified. The subchannel identifying signal is employed atthe receiving station'to selectively operate the proper receiving "connector relay- 50' that the receiving l device correspondingto' the transmitter from which the character sent may be'placed in communication with the transmitter.

Thesystem also includes means'for timing the entry or exit of a subchannel of the expanding channel system. These-timing means comprise relays H2 and I29 of Fig. '1, both of which are actuated to perform-their respective functions under the control of-the transmitting distributor TD. Thus it is seen that the expanding channel system is entirely. automatic in its operation so that subchannels may be cut in or cut out in' accordance with the busy or idle condition thereof. An important feature'of the invention is the provision for stepping blank tape through the subchannel transmittersso that the blank characters perforated therein are not transmitted over the communication channel thereby making the entire signaling time of the communication channel available for the transmission of intelligence.

While the invention has been described in conjunction with a system comprising four subchannels, it is not contemplated that it be limited thereto. It should be obvious to one skilled in the art that the expanding channel system may be arranged to accommodate any desired number of subchannels. It is only necessary to add one or more elements tothe subchannel identifying signals so that the necessary subchannel selection at the receiving station may be effected for the additional subchannels.

The foregoing description of'the' invention has touched upon the transmission of signals in only one direction. It is within the scope of the invention to provide communication facilities over a communication channel in two directions. The two directional communication may be of such a nature that communication is afforded in only one direction at a time or duplex facilities may be provided whereby a communication channel is used for signaling in both directions simultaneously. In either case transmitting equipment such as shown in Figs. 1 and 2 will be provided at the receiving station and the receiving apparatus shown in Fig. 3 will be provided at the 75 transmitting station. For duplex operation the line'relays may be connected in any well known manner to cause'thcse relays to be response to signals receivedfrom the remote station and unresponsive to signals transmitted from the home station to the remote station. The operation of the expanding channel system in either of these cases is substantially as set forth in this specification.

The nature of the invention may be ascertained from the foregoing description of an illustrative embodiment, it being understood that changes inthe invention herein disclosed may be made within the scope of What is claimed without departing from the spirit of the invention.

What is claimed is:

' 1. An expanding channel telegraph system comprising a plurality of transmitters having tongues, a plurality of receivers one corresponding to each of said transmitters, a communicaton channel, a connector relay for each of said transmitters having contacts for connecting said transmitter tongues with said communication channel, means for actuating in a predetermined sequence operative ones of said transmitters and said corresponding relays to send intelligence characters over said communication channel, means for transmitting with each of said intelligence characters a signal identifying the actuated transmitter, and means responsive to said signal to render the corresponding one of said receivers receptive to the transmitted intelligence character.

2. An expanding channel telegraph system comprising a plurality of transmitters having tongues, a plurality of receivers one corresponding to each of said transmitters, a communication channel, a connector relay for each of said transmitters having contacts for connecting said transmitter tongues with said communication channel, means for actuating in a predetermined sequence operative ones of said transmitters and said corresponding relays to send intelligence characters over said communication channel,

' means for transmitting in advance of each of said intelligence characters a signal identifying the actuated transmitter, and means responsive to said signal to render the corresponding one of said receivers receptive to the subsequently transmitted intelligence character.

3. An expanding channel telegraph system comprising a plurality of transmitters, a plurality of receivers one corresponding to each of said transmitters, a communication channel, a connector relay for each transmitter to connect the respective transmitters to said communication channel, means for actuating in a predetermined sequence variable numbers of said relays to send intelligence characters over said communication channel from operative ones of said transmitters, means including one of said relays for transmtting with each of said intelligence characters a signal identifying the transmitter associated with said last named relay, and means responsive to said signal to render the corresponding one of said receivers responsive to the transmitted intelligence character.

4. An expanding channel telegraph system comprising a plurality of transmitters, a plurality of receivers one corresponding to each of said transmitters, a communication channel, a connector relay for each of said transmitters and said receivers to connect .the respective transmitters and receivers to said communication channel, means for actuating in a predetermined mitter, a communication channel, a connector relay for each of said subchannels to connect the subchannel transmitter with'said communication channel, means for periodically preparing for operation all of said connector relays simultaneously, a chain of switching relays to complete the operation of only one of said connector relays, means controlled by each of said connector relays to operate a corresponding switching relay, and means independent of the operation of said switching relays to release a previously operated cneof said switching relays.

6. In an expanding channel telegraph system, a plurality of subchannels each having a transmitter, a communication channel, a connector relay for'each of said subchannels to connect the subchannel transmitter with said communication channel, means for periodically generating an impulseto prepare for operation all of said connector relays simultaneously; a chain of switching relays to complete the operation of only one of said connector relays at a time, circuits controlled by each of said connector relays to operate a corresponding switching relay, and means independent of the operation of said switching relays to release a previously operated one of said switching relays.

'7. In an expanding channel telegraph system, a plurality of subchannels each having a transmitter, a communication channel, a connector relay for each of said subchannels to connect the subchannel transmitter with said communication channel, means for periodically generating an impulse to be applied to all of said connector relays simultaneously, a chain of slow-to-release switching relays to select for operation one of said connector -relays at a time, circuits controlled by each of said connector relays to operate a corresponding switching relay, and means for deenergizing an operated switching relay prior to the generation of said impulse, the release of said deenergized switching relay being delayed by the slow-to-release characteristic until the completion of a subsequent connector relay selection.

8. In an expanding channel telegraph system, a plurality of subchannels each having a code transmitter, a communication channel, a connector relay associated with each of said subchannels to associate the corresponding transmtter with the communication channel, means for operating the connector relays associated with operative subchannels in a prearranged sequence, and means controlled by said connector relays for transmitting a signal identifying the operating subchannel.

9. In an expanding channel telegraph system, a plurality of tape transmitters, a. communication channel, a start-stop distributor connected to said communication channel, a release magnet Y for said distributor, circuits controlled by the tape loop of any. of said distributors to operate said release magnet to cause continuous operation of said distributor when one or more transmitters is operative, and means including said circuits whereby the release magnet is actuated to arrest the operation of the distributor when all of said transmitters are inoperative.

10. In a telegraph system, a communicaton channel, a start-stop distributor connected thereto, a plurality of transmitters having tongues, a connector relay for each transmitter having contacts, and means including said relays to connect in a predetermined sequence operative ones of said transmitters to said distributor for operat on over said communication channel.

11. A telegraph system comprising a communication channel, a plurality of transmitters, means for sending in a predetermined sequence intelligence signals from operative ones of said transmitters together with signals identifying the transmitter, a start-stop distributor connect ed to the other terminal of said communication channel, a bank of storage relays, a group of connector relays, a plurality of receivers, one corresponding to each of said transmitters, means including said distributor for selectively actuating one of said connector relays in response to an identifying signal to render operative one of said receivers, additional means including said.

distributor for storing the intelligence signals in said bank of storage relays, an auxiliary startstop distributor, and means including said auxiliary distributor for communicating the signals stored in said bank of relays to said operative receiver.

PERCY L. MYER. EVAN R. WHEELER. 

